The lead acid battery which uses lead dioxide as a positive electrode active material and lead as a negative electrode active material, and uses sulfuric acid aqueous solution as an electrolysis solution is used in various industries since it is suited for cheap and large electrical current discharge compared to other secondary batteries. Even though a large capacity secondary battery such as lithium ion secondary battery holds the present prosperity, the importance of the lead acid battery is not lost, and the lead acid battery is keenly examined to improve its quality even today.
Recently, there are reports of technology using the activated carbon in regards with, the improvement of the large electrical current discharge characteristic during a short period of time which is the advantage of the lead acid battery, and the improvement of the large cycle characteristics of the discharge depth which is the disadvantage.
The patent document 1 describes that the lead acid battery arranging the lead active material layer are arranged on a surface holding a current collector there between, and the activated carbon active material layer coated with the combined paste having the activated carbon, carbon black, carboxymethylcellulose, and neoprene on to opposite surface to the surface having the lead active material layer has good cycle characteristic simulating the typical charge-discharge cycle in regards with secondary battery for 42V mild hybrid electric vehicle.
Also, the patent document 2 describes the electrodes for the lead acid battery formed with the active material layer including the activated carbon, binder and the conductive agent as an electrode active material, on the surface of the lead active material layer, and the lead acid battery comprising said electrodes. The active material layer including the activated carbon, binder and conducting agent is formed by pulverizing the dry kneaded mixture thereof using the cutter mixer, then the obtained pulverized powder material is adhered on to the lead active material layer, followed by applying the pressure; or it is formed by pasting the active material forming composition obtained by mixing the active material, the binder aqueous solution and the conductive agent on to the lead active layer. This lead acid battery comprising the electrode for the lead acid battery provides the lead acid battery which exhibits higher power compared to that of the conventional one.
Also, the patent document 3 describes that the lead acid battery using the negative electrode prepared by filling the negative electrode mixture paste in which 1 to 5 parts by weight of the activated carbon with respect to the negative electrode active material is added to the lead alloy porous body as the current collector, can hold the high voltage after 0.5 seconds of the electric discharge at −15° C.
Patent document 1: WO2005/027255 (corresponding publication: US Patent Publication No. 2007-104981)
Patent document 2: JP-A 2007-12596 (corresponding publication: US Patent Publication No. 2006-269801)
Patent document 3: JP-A-2003-51306